/*
 * Copyright (C) 2013 Adrian Ulrich <adrian@blinkenlights.ch>
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program. If not, see <http://www.gnu.org/licenses/>.
 */

package net.nullsum.audinaut.util.tags;

import java.io.IOException;
import java.io.RandomAccessFile;
import java.nio.charset.StandardCharsets;
import java.util.HashMap;


class LameHeader extends Common {

    public LameHeader() {
    }

    public HashMap getTags(RandomAccessFile s) throws IOException {
        return parseLameHeader(s, 0);
    }

    public HashMap parseLameHeader(RandomAccessFile s, long offset) throws IOException {
        HashMap tags = new HashMap();
        byte[] chunk = new byte[4];

        s.seek(offset + 0x24);
        s.read(chunk);

        String lameMark = new String(chunk, 0, chunk.length, StandardCharsets.ISO_8859_1);

        if (lameMark.equals("Info") || lameMark.equals("Xing")) {
            s.seek(offset + 0xAB);
            s.read(chunk);

            int raw = b2be32(chunk, 0);
            int gtrk_raw = raw >> 16;     /* first 16 bits are the raw track gain value */
            int galb_raw = raw & 0xFFFF;  /* the rest is for the album gain value       */

            float gtrk_val = (float) (gtrk_raw & 0x01FF) / 10;
            float galb_val = (float) (galb_raw & 0x01FF) / 10;

            gtrk_val = ((gtrk_raw & 0x0200) != 0 ? -1 * gtrk_val : gtrk_val);
            galb_val = ((galb_raw & 0x0200) != 0 ? -1 * galb_val : galb_val);

            if ((gtrk_raw & 0xE000) == 0x2000) {
                addTagEntry(tags, "REPLAYGAIN_TRACK_GAIN", gtrk_val + " dB");
            }
            if ((gtrk_raw & 0xE000) == 0x4000) {
                addTagEntry(tags, "REPLAYGAIN_ALBUM_GAIN", galb_val + " dB");
            }

        }

        return tags;
    }

}
